【作者】 张权；

【导师】 薛春纪；

【作者基本信息】 中国地质大学（北京） ， 矿物学、岩石学、矿床学， 2011， 硕士

【摘要】 新疆是中国重要的有色金属成矿区之一,晚古生代是其最重要的成矿期,而中生代尤其是燕山期,有色金属的成矿作用较为少见。目前,新疆燕山期有色金属成矿仅见于西昆仑和阿尔金造山带以及东天山地区,在西天山地区还未见有燕山期成矿的报道。近年于新疆西天山新发现的七兴铅锌矿,一度被认为是莱历斯高尔-3571矿田海西期成矿系统的有机构成。但笔者通过对七兴铅锌矿区出露的辉长辉绿岩中的锆石进行SHRIMP U-Pb测年,获得186.2±8.4Ma的成岩年龄,加之,矿区常见有硫化物矿脉与基性岩脉共（伴）生,并切穿基性岩脉的现象,综合表明,七兴铅锌矿是燕山期构造-岩浆-热液成矿的产物,而非莱历斯高尔-3571矿田海西期成矿系统的构成。七兴铅锌矿床的成因解译,对正确理解西天山地区的成矿作用和地质演化历史,以及在西天山地区寻找燕山期形成的有色金属矿产,具有十分重要的意义。七兴铅锌矿床石英-硫化物工业矿体呈脉状,产于志留系粉砂泥岩层中。矿体与围岩界线截然,两侧围岩发育硅化等热液蚀变,矿石的矿物组成相对复杂,中-粗晶和交代结构,具有热液充填-交代成矿特点。流体包裹体的研究表明,成矿流体具有中-低温度、中-低盐度、低密度的特点;δ¹⁸OH₂O、δD_H2O组成特征表明,成矿流体来源主体为岩浆水,后期有大气降水的加入;矿石中硫化物δ³⁴S组成特征表明,S的来源应为深源岩浆硫混染了地层硫;铅同位素组成特征表明,成矿金属物质或者来自矿区出露的基性岩浆岩,或者伴随中基性岩浆活动来自下地壳,在成矿过程中混入少部分上地壳物质;矿区出露的辉绿岩脉的主、微量元素特征显示,脉岩形成时处于板内拉张的构造环境,属钙碱性玄武岩系列;七兴铅锌矿床形成于燕山期,燕山早期构造伸展—岩浆活动—铅锌成矿对于七兴矿区应为发生、发展、密切关联的连续地质过程。更多还原

【Abstract】 Xinjiang is one of the important nonferrous metals metallogenetic areas in China. The late Paleozoic is the most important metallogenetic period in Xinjiang. But in Mesozoic, especially in Yanshanian nonferrous metals mineralization was rare. At present, Xinjiang nonferrous metals mineralization in Yanshanian was found only in the Western Kunlun orogenic belt, Altun orogenic belt and Eastern Tianshan. There hasn’t a report of Yanshanian mineralization in Western Tianshan.Qixing Pb-Zn ore deposit was recently discovered in Xinjiang, Western Tianshan. It was regarded as a part of the Lailisigao’er-3571 Hercynian metallogenetic system. In this paper, the author studied SHRIMP zircon U-Pb age of gabbro-diabase in Qixing Pb-Zn ore deposit, and obtained an age of 186.2±8.4Ma. The Zn-Pb sulfide ore-body, paragenied or associated with some basic dikes and cut through the basic dikes. Evidence shows that the Qixing Zn-Pb ore deposit is a product of the Yenshan period structure-magma- hydrothermal mineralization, rather than a part of the Lailisigao’er–3571 Hercynian metallogenetic system.Explaining the genesis of Qixing ore deposit is of great significance to understanding the mineralization and the geological evolution correctly and funding Yanshanian non-ferrous metals ore deposits in Xinjiang, Western Tianshan.The Zn-Pb sulfide ore-body in Qixing ore deposit is vein in silty mud of Silurian system. The Zn-Pb ore is composed by Quartz, Zn-Pb sulfide and many other minerals, and show a complex mineral composition. The minerals are middle-coarsely crystalline and replaced textures in the ores. The ore-forming is hydrothermal filling-replacing style.The ore-forming fluid was middle temperature, low salty and low density.δ¹⁸O_H2O andδD_H2O characteristics show that ore-forming fluid mainly from the magma, at later stage mixed rainfall.The oreδ³⁴S characteristics show that S mainly from the deep magma and mixed small stratigraphic S. The ore Pb-isotopic composition shows that the metals in the ore was from basic rocks in the ore deposit of Qixing ,or from lower crust associated with basic magmatic activities, and in the course of ore-froming it mixed small upper crust materials.Characteristics of trace and rare earth elements suggest that mafic dykes in Qixing ore deposit were most probably formed in rifted environment within plate basalts. The mafic dykes in Qixing ore deposit belongs to the cal-alkaline series.Qixing Pb-Zn ore deposit formed in Yanshanian.The Yanshan period tectonic extension– magma activity– Zn-Pb mineralization was a starting, developing and closely related geological process.更多还原